We use Shopify's SSO (Single Sign-On) to log you into your accounts securely. This also means that users can access the app as long as they have been permitted in your Shopify store's settings.
However, if you are on the Shopify Plus Plan, you can set permissions on an app-level for your staff. This seems like a feature that's only available on this plan at the moment. For more information, here's the link to the relevant Shopify section here: https://help.shopify.com/en/manual/your-account/staff-accounts/staff-permissions#shopify-plus-permissions.